EP0926724A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Patterning of porous silicon using silicon carbide mask
Assignee: Texas Instruments Inc
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Filing: 1998-12-11
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Granted: —
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Expires: 2018-12-11
Abstract
Abstract A method of selectively forming porous silicon regions (106) in a silicon substrate (100). A masking layer (104) of SiC is deposited by PECVD over the substrate (100) using an organosilicon precursor gas such as trimethylsilane, silane/methane, or tetramethylsilane at a temperature between 200 - 500°C. The masking layer (104) of SiC is then patterned and etched to expose the region of the substrate (100) where porous silicon is desired. An anodization process is performed to convert a region of the substrate to porous silicon (106). The SiC masking layer (104) withstands the HF electrolyte of the anodization process with little to no degradation.
Inventors
- 👤 Leland S. Swanson
- 👤 Douglas A. Prinslow
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 01:41
CPC Classifications
H; H10; H10W; H10W10/00; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/692; H10W10/01; H10W10/011; H10W10/012; H10W10/10; H10W10/13; H10D; H10D62/00; H10D62/80; H10D62/83; H10D62/832; H10D62/8325
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
116 words
A method of fabricating a porous silicon region in a substrate
having a isolation region formed therein, comprising the steps
of: patterning and etching said isolation region to expose a
first area of said substrate; depositing, by plasma enhanced chemical vapor deposition
using an organosilicon precursor gas, a layer of silicon carbide
over said substrate including said first area, said depositing
step occurring at a temperature in the range of 200-500°C; patterning and etching said silicon carbide layer to expose
a second area of said substrate within said first area; and forming a porous silicon region in said first area using an
HF electrolyte, wherein said silicon carbide layer protects said
transistor from the HF electrolyte.
Claim 2
Dependent Claim
21 words
The method of Claim 1, wherein said depositing step comprises
depositing by PECUD using an organosilicon precursor gas that
comprises trimethylsilane.
Claim 3
Dependent Claim
30 words
The method of Claim 1 or Claim 2, wherein said step of
patterning and etching said isolation region forms angled
sidewalls having a slope substantially on the order of 45°.
Claim 4
Independent Claim
32 words
The method of any preceding claim, wherein said step of
depositing a silicon carbide layer comprises depositing a silicon
carbide layer having a thickness in the range of 1000 - 5000 Å.
Claim 5
Independent Claim
64 words
The method of any preceding claim, further comprising
performing said step of depositing said silicon carbide layer
using following processing parameters: a carrier gas supplied at
a pressure on the order of 4 Torr and a gas flow in the range of
500-5000 sccm, and a RF power density on the order of 2W/cm 2 at a
frequency on the order of 13.56 MHz.
Claim 6
Independent Claim
68 words
The method of any Claims 1 to 5, wherein said step of
patterning and etching said silicon carbide layer comprises the
step of etching in chlorine with a chamber pressure on the order
of 300 mTorr, a gas flow in the range of 10-50 sccm, and a RF
power density in the range of 0.5 - 1 W/cm 2 at a frequency on
the order of 13.56 MHz
Claim 7
Independent Claim
91 words
The method of any of Claims 1 to 5, wherein said step of
patterning and etching said silicon carbide layer comprises the
step of etching in CF 4 /O 2 /H 2 with a chamber pressure on the order
of 10 - 50 mTorr, a gas flow for H 2 in the range of 0-20 sccm
and for fluorinated oxygen in the range of 10 - 50 sccm, and a RF
power density in the range of 0.5 - 1 W/cm 2 at a frequency on
the order of 13.56 MHZ.
Claim 8
Independent Claim
91 words
The method of any of Claims 1 to 5, wherein said step of
patterning and etching said silicon carbide layer comprises the
step of etching in SF 6 /O 2 /H 2 with a chamber pressure on the order
of 10 - 50 mTorr, a gas flow for H 2 in the range of 0-20 sccm
and for fluorinated oxygen in the range of 10 - 50 sccm, and a RF
power density in the range of 0.5 - 1 W/cm 2 at a frequency on
the order of 13.56 MHZ.
Claim 9
Independent Claim
92 words
The method of any Claims 1 to 5, wherein said step of
patterning and etching said silicon carbide layer comprises the
step of etching in CHF 3 /CF 4 /Ar/O 2 /H 2 with a chamber pressure on
the order of 10 - 50 mTorr, a gas flow for H 2 in the range of 0-100
sccm and for fluorinated argon in the range of 50 - 200 sccm,
and a RF power density in the range of 0.5 - 1 W/cm 2 at a
frequency on the order of 13.56 MHZ.
Claim 10
Independent Claim
35 words
The method of any preceding claim, wherein said step of
forming said porous silicon region comprises anodization in a HF
electrolyte and a current density in the range of 30 - 100
mA/cm 2 .
Claim 11
Dependent Claim
30 words
A substrate having a porous silicon region formed in an
isolation region thereof, said porous silicon region being formed
according to the method of any of Claims 1 to 10.
Claim 12
Dependent Claim
34 words
A semiconductor device comprising a substrate having a porous
silicon region formed in an isolation region thereof, said porous
silicon region being formed according to the method of any of
Claims 1 to 10.
References Cited (Backward Citations)
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